This disclosure relates in general to energy conversion; more particularly, this disclosure relates to conversion of ocean wave energy into rotational shaft energy.
To convert wave energy into rotational shaft energy, a wave turbine may include a wave chamber coupled to an air turbine, with the wave chamber partially submerged in a body of water to provide an oscillating water column therein. In response to wave action of the body of water, the oscillating water column rises and falls, acting as a piston by pushing and pulling air, or another operating fluid, into and out of the wave chamber. A challenge to implementing such wave turbines is efficiently converting the energy of such a bi-directional flow of fluid into useful mechanical energy.
Most turbines are designed to accept flow in a single direction, and are optimized to direct the flow using stator vanes, which channel the fluid to impact and/or progress between turbine blades at a desired flow angle. However, in the case of the wave turbine complex networks of valves are required to avoid drag losses during the “backward” flow. Unfortunately, these complex valve networks increase the complexity of the wave turbine, which can result in increased capital and operating expense; and can make the wave turbine more susceptible to component failure.
One way to avoid such valve networks is to use a bi-directional turbine, one example of which is a Wells turbine. In a Wells turbine, the blades are configured to receive the bi-directional flow to continuously rotate a shaft. Bi-directional flow, however, inhibits optimization, and as such, the efficiency and power output of Wells turbines is generally limited. This requires the turbines to be larger than desired, again resulting in increased capital and operating expenses.
Therefore, what is needed is an energy conversion system and method that overcomes one or more of the challenges described above.